How to solve error_too_many_redirects in codeigniter?

Question

CodeIgniter

There is a small site on codeigniter, everything seems to work, but (not on all) on some devices, when entering the admin panel, it displays an error_too_many_redirects error. I tried it myself even through vpn, from different devices, I didn’t come across this, the login function itself is primitive, what could be the problem? Maybe the problem is in the server settings? Here is the controller

<?php defined('BASEPATH') OR exit('No direct script access allowed');

class User extends MY_Admin
{
  protected $data = array();

  function __construct()
  {
    parent::__construct();
    $this->load->model('AdminModel');
  }

  public function index()
  {
    if (!$this->logged_in) {
      header("Location: /admin_folder/user/login");
      return false;
    }

    return $this->load->view('/admin_folder/index');
  }

  public function login()
  {
    if ($this->logged_in) {
      header("Location: /admin_folder/user/login");
      return false;
    }

    if (isset($_POST['password']) && isset($_POST['login']) &&
      !empty($_POST['password']) && !empty($_POST['password'])) {

      $data = array(
        'login' => htmlspecialchars($_POST['login']),
        'password' => md5($_POST['password'])
      );
      $check = $this->AdminModel->check_login($data);
      if ($check) {
        $_SESSION['user_data'] = $data;
        header("Refresh:0");
      } else {
        $data['response'] = 'login or password wrong';
      }
    } else {
      $data['response'] = '';
    }
    return $this->load->view('/admin_folder/login', $data);
  }

  public function logout()
  {
    session_destroy();
    header("Location: /admin_folder/user/login");
  }
}

Answer 1

in the login() method you check if the user is authorized - you send him again to the login() method, and so on in a circle.